netdev - RE: [PATCH net-next 0/8] More accurate PHC<->system clock synchronization

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Date:   Fri, 9 Nov 2018 18:12:05 +0000
From:   "Keller, Jacob E" <jacob.e.keller@...el.com>
To:     Miroslav Lichvar <mlichvar@...hat.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     Richard Cochran <richardcochran@...il.com>,
        Marcelo Tosatti <mtosatti@...hat.com>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        Michael Chan <michael.chan@...adcom.com>
Subject: RE: [PATCH net-next 0/8] More accurate PHC<->system clock
 synchronization

> -----Original Message-----
> From: Miroslav Lichvar [mailto:mlichvar@...hat.com]
> Sent: Friday, November 09, 2018 2:15 AM
> To: netdev@...r.kernel.org
> Cc: Richard Cochran <richardcochran@...il.com>; Keller, Jacob E
> <jacob.e.keller@...el.com>; Miroslav Lichvar <mlichvar@...hat.com>; Marcelo
> Tosatti <mtosatti@...hat.com>; Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>;
> Michael Chan <michael.chan@...adcom.com>
> Subject: [PATCH net-next 0/8] More accurate PHC<->system clock synchronization
> 
> RFC->v1:
> - added new patches
> - separated PHC timestamp from ptp_system_timestamp
> - fixed memory leak in PTP_SYS_OFFSET_EXTENDED
> - changed PTP_SYS_OFFSET_EXTENDED to work with array of arrays
> - fixed PTP_SYS_OFFSET_EXTENDED to break correctly from loop
> - fixed timecounter updates in drivers
> - split gettimex in igb driver
> - fixed ptp_read_* functions to be available without
>   CONFIG_PTP_1588_CLOCK
> 
> This series enables a more accurate synchronization between PTP hardware
> clocks and the system clock.

Thanks for doing this, Miroslav!

> 
> The first two patches are minor cleanup/bug fixes.
> 
> The third patch adds an extended version of the PTP_SYS_OFFSET ioctl,
> which returns three timestamps for each measurement. The idea is to
> shorten the interval between the system timestamps to contain just the
> reading of the lowest register of the PHC in order to reduce the error
> in the measured offset and get a smaller upper bound on the maximum
> error.
> 
> The fourth patch deprecates the original gettime function.
> 
> The remaining patches update the gettime function in order to support
> the new ioctl in the e1000e, igb, ixgbe, and tg3 drivers.
> 
> Tests with few different NICs in different machines show that:
> - with an I219 (e1000e) the measured delay was reduced from 2500 to 1300
>   ns and the error in the measured offset, when compared to the cross
>   timestamping supported by the driver, was reduced by a factor of 5
> - with an I210 (igb) the delay was reduced from 5100 to 1700 ns
> - with an I350 (igb) the delay was reduced from 2300 to 750 ns
> - with an X550 (ixgbe) the delay was reduced from 1950 to 650 ns
> - with a BCM5720 (tg3) the delay was reduced from 2400 to 1200 ns
> 

Impressive results!

For the main portions and the Intel driver changes this is

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>

Regards,
Jake

> 
> Miroslav Lichvar (8):
>   ptp: reorder declarations in ptp_ioctl()
>   ptp: check gettime64 return code in PTP_SYS_OFFSET ioctl
>   ptp: add PTP_SYS_OFFSET_EXTENDED ioctl
>   ptp: deprecate gettime64() in favor of gettimex64()
>   e1000e: extend PTP gettime function to read system clock
>   igb: extend PTP gettime function to read system clock
>   ixgbe: extend PTP gettime function to read system clock
>   tg3: extend PTP gettime function to read system clock
> 
>  drivers/net/ethernet/broadcom/tg3.c          | 19 ++++--
>  drivers/net/ethernet/intel/e1000e/e1000.h    |  3 +
>  drivers/net/ethernet/intel/e1000e/netdev.c   | 42 ++++++++++---
>  drivers/net/ethernet/intel/e1000e/ptp.c      | 16 +++--
>  drivers/net/ethernet/intel/igb/igb_ptp.c     | 65 +++++++++++++++++---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c | 54 +++++++++++++---
>  drivers/ptp/ptp_chardev.c                    | 55 ++++++++++++++---
>  drivers/ptp/ptp_clock.c                      |  5 +-
>  include/linux/ptp_clock_kernel.h             | 33 ++++++++++
>  include/uapi/linux/ptp_clock.h               | 12 ++++
>  10 files changed, 253 insertions(+), 51 deletions(-)
> 
> --
> 2.17.2